1. Field of the Invention
This invention relates to a lock device, in which a key and a lock having variable bit and ward patterns, respectively, and more particularly to a lever tumbler lock device, in which one or both bit members of the key and one or both ward member of the lock, may be moved in cooperative relation and then fixed rigidly, respectively.
2. Description of the Prior Art
Locks which are available widely in the market may be classified into box locks, dial locks, time locks and combinations thereof.
The box locks may be further classified into a latch bolt type and a dead bolt type. In the dead bolt type lock, a bolt is moved by means of a key, in a manner that ward members provided within a lock may be moved by a specific key, when the key is turned, so that the lock may be opened or closed. This type of locks are referred to as lever tumbler locks and find a wide application.
The lever tumbler lock device, as has been described earlier, should be used in combination of a key and a lock. Thus, many attempts have been proposed to modify or improve the secrecy of a lock and a key. However, if a key is duplicated or stolen, then the secrecy of a lock is lost. On the other hand, there are often manufactured master keys according to the mass production of locks and keys. Thus, there is a risk that the secrecy of a lever tumbler lock is sometimes impaired.